When an aircraft pass through the air, it creates pressure waves in front of it and behind it in much the same way the bow and stern of a boat create waves. These pressure waves travel at the speed of sound. The pressure waves in the front of the aircraft create a rise in pressure (compression) followed by a decrease to a negative pressure at the tail, ending in a sudden return to the ambient air pressure. Above the speed of sound, the aircrafts radiated compression waves are heard on the ground as an explosion or sonic boom. This “overpressure profile” is known as an N-wave because of its shape.
The “boom” is experienced when there is a sudden change in pressure, therefore an N-wave causes two booms—one when the initial pressure rise from the nose hits, and another when the tail passes and the pressure suddenly returns to normal. This leads to a distinctive “double boom” from a supersonic aircraft. The power, or volume, of the shock waves is dependent on the quantity of air that is being compressed, accelerated, and recompressed, and thus, dependent on the size and shape of the aircraft. The “length” of the boom from front to back is dependent on the length of the aircraft to a power of 3/2. The longer the aircraft, the more “spread out” their booms, which are a therefore less powerful boom.
Because of the often extreme levels of noise heard on the ground as a result of the sonic boom, flight overland at speeds approaching and beyond the speed of sound is severely limited. Current Federal Aviation Administration regulations prohibit any commercial supersonic flight overland. The regulations were promulgated at a time when typical supersonic aircraft had cruise sonic boom signatures that were perceived by the public at large to be unacceptably loud. A feature many of these aircraft had in common was a pressure signature in cruise, that when propagated to the ground, coalesced into two distinct nose and tail shocks, e.g. an N-wave. Because of the sonic boom generated by conventional aircraft during supersonic flight operations, flight times overland are typically increased because aircraft are regulated to fly at lower speeds.
It is with respect to these and other considerations that the disclosure herein is presented.